Island



(No Model.)

0. A. SMITH. DRAFTING TRIANGLE.

No. 437,870. Patented Oct. 7, 1890.

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.Fig. 3 is a sectional View, on an enlarged v UNITED STATES PATENT OFFICE.

CHARLES A. SMITH, OF PAWVTUOKET, RHODE ISLAND.

DRAFTING- TRIANG LE.

SPECIFICATION forming part of Letters Patent No. 437,870, dated October '7, 1890.

Application filed July 1, 1890.

To aZZ whom it may concern:

Be it known that I, CHARLES A. SMITH, of lawtucket, in the county of Providence and State of Rhode Island, haveinvented a new and useful Improvement in Drafting-Triangles; and I hereby declare that the following is a full, clear, and exact description of the same, reference being had to the accompanying drawings, forming part of this specification.

This invention has reference to an improvement in triangles used for drafting and similar purposes.

The object of this invention is to produce a triangle combining lightness with strength, which will not when in use obstruct the drawing as much as is the case with triangles as heretofore constructed, and which can be more firmly held and more accurately moved than the older form of triangles.

Triangles used for drafting have heretofore been made of wood, rubber, or metal. As the three sides of such triangles must have rigid edges forming perfect and true straight lines, the triangles have heretofore been made either solid, provided with a hole usually intended for hanging the triangle on pins when not in use, or they have been constructed with the three sides of the triangle of considerable width, so as to secure the rigid edges absolutely essential in a drafting-triangle. These wide sides of such a triangle obstruct the drawing on which they are used and make their frequent movement over the drawingnecessary. The wide surface also gutters and transports the impurities, causing the surface of the drawing to become dirty. The wide surface of the triangle frequently causes delay, as the triangle cannot be moved over lines drawn with ink while the ink is still soft or moist.

To overcome these defects and produce a superior triangle, the invention consists in the novel construction by which the narrow edges of the triangles are braced and connected with each other by wire braces, as will be more fully set forth hereinafter;

Figure 1 is a side View of a triangle the rectangular sides of which are of equal length. Fig. 2 is a side View of a triangle the rectangular sides of which are of different length.

scale, of one of the sides of my improved triangle.

In the drawings the number 5 indicates the Serial No. 357,351. (No modal.)

sides of the triangle, and 6 the wires extending from one of the sides to the other side or sides. The wires 6 cross each other at right angle and are secured at their ends to the sides 5. At the point where these wires cross each otherI prefer to secure the Wires to each other. This can be readily done by tinning or otherwise plating the wire when laid in the crossed position, either before or after the wires are secured to the sides 5. In practice I find the woven wire-cloth of commerce well adapted for the purpose, and in Fig. 3 I have shown such a woven wire fabric on an enlarged scale, so as to show the construction more clearly. The side piece 5 is shown of u-shaped cross-section forming a groove on the inner side, in which the woven wire fabric 6 is secured.

The sides 5 of the triangle may he made of any suitable material.

I prefer to form the sides of metal with the groove shown in Fig. 3 on the inner side. The metallic web 6 I cut of such shape and size that in the fiat condition it enters and nearly fills the groove. I now secure, by means of solder, the edges of the metallic web 6 in the groove of the sides 5.

The edges 5 can be made of very small cross section. One-tenth of an inch square I find to answer for ordinary drafting-triangles.

The triangles so made are light,practically transparent, they presentlit'tle surface in con tact with the paper, can be firmly held as the fingers are pressed on the wire framing, and are cleaner than the wide-surfaced triangles as heretofore constructed. They are not affected by changes in temperature or by the hydromatic condition of the air. They are also simple and cheap in construction.

Having thus described my invention, I claim as new and desire to secure by Letters Patent-- 1. A drafting-triangle consisting of the sides 5, forming the edges of the triangle, and the crossed wires 6, having their ends secured to the sides 5, as described.

2. In a drafting-triangle, the combination of the sides 5, provided on their inner sides with a groove, and the wire webbing 6, the edges of which are secured in the groove of the sides, as described.

CHARLES A. SMITH.

\Vitnesses:

J. A. MILLER, Jr., M. F. BLIGH. 

